1. Field of the Invention
This invention relates to a wrenching tool, and in particular to a tool useful for removal of fasteners which are in recessed locations.
2. Brief Statement of the Prior Art
Frangible fasteners are used extensively in the aerospace industry. These fasteners employ a threaded locking collar which is joined by a notched neck to a wrenching ring which shears from the collar when the applied torque exceeds a predetermined torsional loading. Often the threaded locking collar has an upset portion, usually a slightly elliptical shape to provide a frictional spring lock that prevents the collar from spinning off in the event that the residual tension on the fastener is lost.
These fasteners are applied with wrenching tools which engage the wrenching ring to apply the threaded collar and twist the wrenching ring from the threaded collar when the predetermined torsional loading is exceeded.
It is frequently desirable to loosen or remove threaded locking collars from assembled fasteners. Heretofore, no entirely suitable tool has been devised for this application. The threaded collar commonly has a cylindrical base which tapers into a smaller diameter cylindrical neck. The cylindrical portions of these collars are narrow and are difficult to grasp with conventional tools such as pliers, vise grip clamps, etc. The difficulties with removal are even more acute when the locking collars are recessed. This frequently occurs when the locking collars are seated within the channels and are inaccessible to most tools. Additionally, the use of non-standard tools for loosening or removing of the frangible fasteners is objectionable as such tools can damage the surfaces of the assembled parts.
A fastener collar removal tool is disclosed in U.S. Pat. No. 4,762,030 in which a collet clutch member is threadably received within a collet sleeve. The tool has a central pin which is rotationally immobilized and which has a ball detent that seats in a groove of the collet clutch member to permit the collet to be compressed about the fastener. While, this removal tool is suitable for use with clean, newly applied fasteners, however, it is not suitable for use with stuck or corroded fasteners since the grip of the collet fingers about the collar is limited by the torque which is sufficient to pop the detent ball from its restraining groove in the pin.
In my prior U.S. Pat. No. 4,862,773, I disclose and claim a fastener collar removal tool which also has a collet member. The device of that patent is particularly suitable for use with a power driven ratchet wrench which is reversible to loosen the collet from the fastener collar after its removal. When used with hand ratchet wrenches, it is desirable to provide a mechanism to eject the collar after its removal.